I "celebrated" a couple of days early by getting through a borrowed truncated cycle of the symphonies and Das Klagende Lied by Tilson Thomas. By "truncated" I mean that the cycle didn't have M3, M6, & M7. Some of the symphonies were downloads, and the others were retail SACDs. The original owner of these disks, sadly, passed away earlier this year, and the custodian of the deceased gentleman's assets asked me to listen to them as to what I thought of the cycle. Sadly, I'm not that impressed overall with Tilson Thomas' traversal of the symphonies. About the best of what I heard were M1 and M4, plus Das Klagende Lied. To top off the Tilson Thomas read-through, I listened to Dudamel's M1 (also borrowed from the same source).
I'll celebrate Mahler's birthday tomorrow by listening to one of my many M2 recordings, one I just came across on loan from my above source.
Wade